Motors in compressors for use in devices like refrigeration cycle apparatuses, an increased torque is required during compression of a refrigerant and a reduced torque is required during discharge of the compressed high pressure refrigerant, thereby causing torque fluctuations.
Generation of such torque fluctuations results in deflections in a shaft, causing vibration and noise when compressors are operated. To suppress such vibration and noise, conventional techniques represented by Patent Literature 1 to be described below employ a component called a balance weight in a rotor. Such a balance weight is generally made of a non-magnetic material to avoid a reduction in magnetic force of a motor.